1. Field of the Invention
The invention relates to a toner for electrophotography, which may be suitably be used for developing electrostatic latent images formed on the surface of an electronic latent image carrier (photoconductive insulator) such as a photoconductor drum, as well as a developing agent for electrophotography containing the toner for electrophotography, an image forming method, and an image forming device using the developing agent for electrophotography.
2. Description of the Related Art
Electrophotography is well known as a conventional method for visualizing electric image data on recording media such as recording paper. In electrophotography, first forming an electrostatic latent image by exposing in the shape of an image using an exposing device, etc., after evenly electrically charging the surface of an electronic latent image carrier (photoconductive insulator) such as a photosensitive drum using a charging device, e.g., a corona discharger; next, forming a visible image (toner image) by developing the electrostatic latent image by means of causing either a one-component electrophotography developing agent or a two-component electrophotography developing agent containing an electrically charged toner to adhere to the electrostatic latent image; then transferring the visible image (toner image) to recording media such as recording paper etc.; and finally fixing the visible image (toner image) by melting, solidifying and fixing by means of a process such as pressing, heating, press-heating, and light beam irradiating, thereby a desired image is formed on the recording media.
It is preferable that the toner has high performance capabilities because the quality of images formed by the electrophotography is highly dependent on its performance capabilities such as electrostatic property for causing it to adhere to the electrostatic image, and fixing property for causing it to be melted so as to be fixed on the recording media.
The toner is made up of a charging control agent, a coloring agent, etc., contained in a binder resin, and as the binder resin, a polyester resin, a styrene-acrylic resin, an epoxy resin, etc., are commonly used. As these substances consist of monomers having polar groups such as the COOH group or the OH group at the ends, showing relatively negative polarity and hygroscopic characteristics in response to humidity, wherein a toner using one of these as a binder resin, especially, a toner using polyester resin as a binder resin, tends to cause insufficient charging, while if it is made a positive polarity toner, reverse charging or insufficient charging tend to occur. Thus, these toners are not sufficient from the standpoint of the electrostatic property. Any attempt to replace the COOH group or the OH group in those binder resins so as to remove polarities introduces another problem in that it makes them too difficult and too expensive to manufacture. Moreover, although the electrostatic property can be improved to some degree by polymerizing the binder resins, polymerization in turn causes deterioration in the fixing property.
Electrostatic property and the fixing property are in an antinomic relation to each other, so that no toner for electrophotography providing these charging and fixing property superior balance, nor are any developing agent for electrophotography using such a toner, image forming method, and image forming devices using such a toner available on the market today, thus allowing development of demand.
The intention of the present invention is to solve such problems of the prior art and to achieve the following object. The object of the present invention is to provide a toner for electrophotography capable of providing well-balanced electrostatic property and fixing property during the image forming process hence forming images of high quality in a stable manner, as well as a developing agent for electrophonic photography, an image forming method, and an image forming device using the toner for electrophotography.
The toner for electrophotography of the present invention contains at least one kind of cyclic compound selected from cyclic oligomers and cyclic polymers that do not essentially have any terminal group. Using such a toner for electrophotography makes it possible to improve the fixing property without sacrificing the electrostatic property, hence enabling it to form images of high quality by maintaining the electrostatic property and the fixing property possessing superior balance during the image forming process.
The developing agent of the present invention contains at least the toner for electrophotography of the present invention. Using such a developing agent for electrophotography makes it possible to improve the fixing property without sacrificing the electrostatic property, hence enabling it to form images of high quality by maintaining the electrostatic property and the fixing property possessing superior balance during the image forming process.
The image forming method of the present invention includes at least an electrostatic latent image forming process for forming electrostatic latent images on an electrostatic latent image carrier, a developing process for developing the electrostatic latent images and forming visible images using the developing agent for electrophotography of the present invention, and a transfer process for transferring the visible images to a transfer material. In the image forming method, electrostatic latent images are formed on the electrostatic image carrier during the electrostatic latent image forming process. Developing the electrostatic latent images using the developing agent for electrophotography of the present invention during the development process forms visible images. The visible images are transferred to the transfer material during the transfer process.
The image forming device of the present invention includes at least an electrostatic latent image carrier, an electrostatic latent image forming means for forming electrostatic latent images on the electrostatic latent image carrier, a developing means containing a developing agent for electrophotography of the present invention for developing the electrostatic latent images and forming visible images, and a transfer means for transferring the visible images to a transfer material. In the image forming device, the electrostatic latent image forming means forms electrostatic latent images on the electrostatic latent image carrier. The developing means contains the developing agent for electrophotography and develops the electrostatic latent images to form visible images. The transfer means transfers the visible images to the transfer material. As a result, images are formed on the transfer material.